Terror Behind the Walls, Philadelphia, PA

America’s largest haunted house is located inside the massive castle-like walls of Eastern State Penitentiary, a real-life former prison believed to be one of the most haunted spots in the country and frequently featured on paranormal TV shows - Ghost Hunters did five episodes here. In its 22nd year, this extraordinary theatrical production is consistently ranked among the best - and scariest - haunted attractions in the country.